Treatment of styrene type compounds



Patented Oct. 6, 1942 TREATMENT OF TYPE COMPOUNDS Frank J. Soday, Upper Darby, -Pa., assignor to y The United Gas Improvement Company, a corporation of Pennsylvania No Drawing. Application April 4, 1939,

Serial No. 265,941

8 Claims.-

It has been found to be extremely diflicult to produce resins of this type in large scale operations from materials derived from light oil without imparting considerable discoloration to the final product.

In certain instances, discoloration is so serious as to completely destroy the usefulness of the resulting resin for many purposes.

It is an object 'ofthis invention to provide a method by which resins of clear water-white transparency may be prepared from light oil fractions containing aromatic olefines having the styrene structure as a nucleus.

More particularly, it is an object of this invention to provide a method by which such fractions may be stored, handled, conveyed, processed,

vide a. method for constructing process vessels,

piping, valves, fittings, storage tanks, shipping tanks and containers, fractionating columns, condensers, agitators, and other equipment used in the production, handling, and processing of such processed or stored, or otherwise handled or.ma-. I nipulated prior to or during polymerization or both, results in resins which are free from undesired discoloration.

In carrying out my invention, equipment used and/or polymerization of such fractions is either constructed entirely of ma nesium or of an alloy in which magnesium is the principal ingredient, or such equipment is lined with magnesium or such magnesum alloy.

In other words, the construction is such that surfaces coming into'contact with the material in process are of magnesium or of a magnesium aHoy in which magnesium is the principal ingredient.

I have found that when such fractions, or solutions or mixtures thereof are permitted to remain in contact with certain metals such as copper, iron, Monel metal, brass, bronze, steel, and admiralty metal, which are the chief engineering materials and are the ones most commonly used in' the construction of industrial equipment of the character involved, for an appreciable length of time, either the material itself or its polymerization product or both become undesirably discolored.

Illustrative of the effect of various metals on the color of unpolymerized and polymerized styrene derived from light oil are the following examples.

Example 1 Storage and processing entirely free from resultant discoloration may be efiected, of course, in the absence of metals. However, as a practical matter, it is usually necessary to resort to metallic equipment in industrial processes.

For the purpose of affording a control, a monomeric light oil styrene fraction, containing 55.7% styrene by weight, was placed-in a glass vessel which had been thoroughly cleaned to remove all possible traces of metal. The container was then sealed and stored at a temperature of -5 C. to prevent polymerization of the sample. The sample was allowed to remain in storage for one month.

This fraction of monomeric styrene was then placed in a'glass bomb in the presence of nitrogen and was heated for eight days at C. followed by heating for two days at C After distilling off unpolymerized material in a vacuum oven at a pressure of approximately one millimeter, abso-- lute,-. there was obtained a clear, water-white transparent polystyrene resin having a melting P int of l79 C.

The polystyrene resin thus obtained was molded at a temperature of 200 C. and a pressure of 2,000 pounds per square inch for a period of three minutes. The molded article thus produced was colorless and transparent. Its color on the standin the storage and processing such as distillation 5 ard Gardner color scale was 1.6.

Example 2 and to prevent polymerization of the sample was stored at C. for one month. During this time the color ofthe styrene fraction rapidly dark- I ened, acquiring a distinct yellow-orange tint after only four days. At the end of the storage period, the fraction was dark orange in color and con- I siderable insoluble material was present.

After decantation, this discolored monomeric styrene fraction was placed in a glass bomb and heated for eight days at approximately 100 C. in an atmosphere of nitrogen, followed by heating for two days at 145 C. Unpolymerized material was then removed by distillation in a vacuum oven at a temperature of 100 C. and a pressure of one, millimeter of mercury absolute.

The polystyrene resin thus obtained possessed a definite orange color. From this resin there was produced a molded article by applying a pressure of 2,000 pounds per square inch for.- a period of three minutes ata temperature of 200 C. This'molded object, had a color of 5.1 on the standard Gardner color scale.

Example 3 Another sample of the same monomeric styrene fraction as .used in the previous example was similarly stored in a sealed glass container for a period of one month at a temperature of --5 C.

, in the presence of freshly cleaned strips of iron.

This fraction became slightly discolored during storage.

It was then polymerized in a glass bomb in an atmosphere of nitrogen by heating for eight days at 100 C. followed by heating for two days at 145 C. Unpolymerized material was removed in a manner similar to that described in.Example 2.

The resultant resin was molded at 200 C. and a pressure of 2,000-pounds per square inch for three minutes. The color of the resulting specimen was found to be 2.9 on the standard Gardner color scale.

Example 4 This example illustrates the inert nature of magnesium when employed for my purposes.

Example 5 A monomeric light oil styrene. fraction, containing 55.7% styrene by weight, was placed in a glass vessel which had been thoroughly cleaned to remove all possible traces of metal. The container was then sealed and stored at a temperature of -5 C. for a period of six months.

This fraction of monomeric styrene was then placed in a glass bombin the presence of nitrogen and heated for eight days at 100 C., followed by heating for two days ,at 145 C. After distilling oil unpolymerized material in a vacuum Example 6 Another portion of the same styrenefraction was then stored for a period of six months in the presence of metallic magnesium at -5'C. The color of the fraction was unchanged.

This fraction was then placed in a glass bomb in the presence of nitrogen and heated for eight days at 100 C., followed by heating for two daysat 145 C. After distilling ofl unpolymerized material in a'vacuum oven at a pressure of approximately one millimeter of mercury, absolute, there was obtained a clear, water-white transparent styrene resin having. a melting point This styrene fraction was then heated in a glass bomb in an atmosphere of nitrogen for eight days at 100 C., followed by heatin'g'for two days at 145 C. Unpolymerized material was removed in a vacuum oven. A colorless polystyrene resin was obtained, having a melting point of 186 0.

This resin was molded at a temperature of 200 C. and a pressure of 2,000 pounds per square inch for a period of three minutes. of the molded object was 1.3 on the standard Gardner color scale. It was clear, colorless and transparent and in every respect comparable in quality to the molded object produced in Example 1. Even longer storageperiods may be used if desired, 85' shown by the following examples.

The color of 177 C. a

The polystyrene resin thus obtained was-molded at a temperature of 200 C. and a pressure of 2,000 pounds per square inch for a period of three minutes. The molded article thus produced was water-white and transparent. Its color on the standard Gardner color scale was 0.9.

The results of the above examples illustrate the eflects of storage of styrene fractions in con.- tact with glass and various metals. Iron and loys in which magnesium is a principal ingre-' dient.

Accordingly, clear water-white transparent polystyrene type resins may be prepared from fractions derived from light oil of the character described when process vessels, piping, valves, flttings, storage. tanks, shipping tanks and contain-,

ers, fractionating columns, condensers, agitators and other equipment for the processing, handling, conveying, storage and transportation of a magnesium-aluminum (10-90, 30-70, 88-42, and 85-15), magnesium-aluminum-manganese (26.4- 71.32.3), magnesium-aluminum tellurium (32.5- -62.5), etc.

In general, alloys of magnesium in which magnesium isone of the principal constituents, might be used since thepresence of magnesium will improve even those metals which are otherwise undesirable. The composition of the alloys given above is by way of illustration only, since the composition of each alloy can be modified over fairly wide limits without departing from the spirit of the invention.

Preferably, however, such alloys are free from substantial quantities of metals which in themselves have a characteristic discoloring action.

As pointed out above, metallic magnesium or the magnesium alloys herein described may be Other methods of coating include electroplating, dipping, flowing molten metal through the parts or system, etc. I

In the preparation of synthetic resins by polymerization one major difiiculty encountered is 'the removal of the polymerized product from the polymerization vessel or from a mold in which the resin has been cast.

For example, polystyrene obtained by the polymerization of substantially pure monomeric styrene, frequently adheres to the walls of the polyremoved only with great difliculty.

To overcome this difiiculty the polymerization may be effected in apparatus constructed to permit its removal from the polymerized product by stripping from the product, by fracturing of the apparatus, or by extrusion of the product from the apparatus.

As an example, unpolymerized or partially polymerized material may be cast into molds constructed to permit stripping or fracturing, or into molds 'from which the cast objects may be extruded. The polymerization is then effected or completed in much molds, for instance, by the application of heat.

For example, polystyrene which has been prepared in a rod shaped mold can be removed by placing the mold in a suitable holder and extruding the polystyrene core by the introduction of a rod or cylinder which is slightly smaller in diam-.

Homologues of styrene contained in the light,

oil fractions with which my invention is particularly concerned include (a) nuclear alkylated or arylated styrene, such as orthomethyl styrene, metamethyl styrene, and paramethyl styrene, (b) substituted styrenes in which the substituent group, either alkyl or aryl, or alkyl-aryl in character, is located on the side chain of the styrene merizing vessel or mold so firmly that it can be Such compounds as well as styrene itself may for convenience be defined generically as aromatic olefines containing the styrene structure as a nucleus.

While it is, of course, preferred to apply the invention to all surfaces within which any such light oil fraction is held from its production to its polymerization, or other utilization, it is, of course, to be understood that the invention may be applied in part to this sequence with corresponding advantages. For instance, the invention may be applied in Whole or in part to production equipment, or to conveying or other handling equipment, or to storage equipment, or to polymerizing equipment. In other words, improved results over the use of metals such as iron and copper may be obtained by holding such fraction for at least a part by surfaces of magnesium or of an alloy in which magnesium is a principal ingredient.

For example, if the styrene fraction is dis- Furthermore, a portion of the surface by which the light oil fraction is held may be of some other material of similar inert characteristic such, for instance, as glass, ceramic material, quartz, the noble metals, lead (as in my copending application Serial No. 256,860, filed February 17, 1939), aluminum (as in my copending application, Serial No, 265,939, filed April 4, 1939) nickel (as in my copending application, Serial No. 277,166, filed June 3, 1939) tin(as in my copending application, Serial No. 277,168, filed June 3, 1939), and zinc (as in my copending application, Serial No. 265,940, filed April 4, 1939).

The invention is of especial importance in polymerization by casting, wherein highly desirable results have been obtained. The term casting as more particularly used is applied to completing the polymerization of a previously partially polymerized fraction of the character described in vessels or molds having the shape of the final product.

In the claims the following terms have the following meanings:

The term magnesium," unless otherwise modified, is intended to embrace pure and commercial magnesium and alloys in which magnesium is the principal ingredient. Such alloys are of large number and can be found in any standard handbook on the subject.

The term metallic magnesium" is intended to embrace pure and commercial magnesium.

It is to be understood that the above particular description is by way of illustration, and that changes, omissions, additions, substitutions, and/or modifications might be made within the scope of the claims without departing from the spirit of the invention which is intended to belimited only as required by prior art.

I claim: 1. A process for polymerizing a light oil fraction having as a principal constituent an aromatic olefine containing the styrene structure as a nucleus which comprises polymerizing said fraction by means of heat in a container having its surfaces in contact with said fraction of magnesium and free from substantial amounts of copper and iron. w

2. A process for polymerizing a light oil styrene fraction which comprises polymerizing said fraction by means of heat in a container having its surfaces in contact with said fraction of magnesium and free from substantial amounts of copper and iron.

3. A process for polymerizing a light oil methyl styrene fraction which comprises polymerizing said fraction by means of heat in a container having its surfaces in contact with said fraction of magnesium and free from substantial amounts of copper and iron.

4. A process for polymerizing a light oil fraction having as a principal constituent an aroing its surfaces in contact with said fraction of magnesium and free from substantial amounts of copper and iron and having the shape of the desired final product, and polymerizing said fraction in said form by means of heat.

6. A process for polymerizing alight oil methyl styrene fraction which comprises placing said fraction prior to complete polymerization into a form having its surfaces in contact with said matic olefine containing the styrene structure as .fraction of magnesium and free from substantial amounts of copper and iron and having the shape of the desired final product, and polymerizing said fraction in said form by means of heat.

'7. In the heat processing of a light oil fraction having as a principal constituent an aromatic olefine containing the styrene structure as a nucleus, the step of confining said fraction during said processing within walls having their surfaces in contact with said fraction of magnesium, said surfaces in contact withsaid fraction being substantially completely free from iron and copper.

8. In the heat processing of a light oil fraction having as a principal constituent an aromatic olefine containing the styrene structure as a nucleus, the step of confining said fraction during said processing within walls having their surfaces in contact with said fraction of metallic magnesium. said surfaces in contact with said fraction being substantially completely free from iron and copper.

FRANK J. SODAY. 

